I'm not sure I understand Putin's fear of a NATO invasion. It may be typical Stalinist era paranoia on Putin's part, but it's been very useful in his drive to expand Russia out to the old borders of the Soviet Union. NATO has been going slack for 30 years but Putin's latest naked aggression will make NATO's eastern boundary a very tough nut to crack now. Putin has revived NATO.We've been working on surrounding Russia for many years. We broke our agreements NOT to expand NATO near their borders since WWII. The NATO moved into 14 close proximity nations to Russia. Russia is just doing what they must.